Media captionSome people slept out overnight in the rain to guarantee their viewing spots

Well-wishers have already started setting up camp outside St James's Palace in central London where Prince George, the three-month-old son of the Duke and Duchess of Cambridge is to be christened.

But after the intense - perhaps at times frenzied - interest in his birth, the christening is set to be low key.

By royal standards the chapel is a small, even intimate place to christen a future king.

The tradition would be to hold the service in the Music Room of Buckingham Palace.

But the Duke and Duchess of Cambridge are again doing things their way and have chosen the Chapel Royal.

Image caption
Prince William was held by his mother and surrounded by European royals at his baptism in 1984

It is where the duchess was confirmed into the Church of England ahead of her wedding and it is a place that must hold some painful memories for the duke.

In the days before her funeral, the coffin of his mother, Diana, rested here.

I don't think they want it to be overly royal, overly posh or overly formalPenny Junor

It was where her family paid their respects privately ahead of her very public funeral.

Do not expect this christening to feel like a grand state occasion.

The guest list will be small and media access is being carefully managed - something that has come as no surprise to royal author, Penny Junor.

"I think they want this to be a private, family, normal kind of event," she says.

"I don't think they want it to be overly royal, overly posh or overly formal. They just want to get their child christened."

Since the prince's birth three months ago, the duke and duchess have naturally been fiercely protective of their son.

So today's christening will be a rare chance to see the youngster.

The last time was back in August and then in a photograph taken by his grandfather, Michael Middleton.

Historic photo

As with any royal christening, the nods to tradition will be plenty.

When Prince William was christened in 1982 he was dressed in the traditional lace and satin robe made for Queen Victoria's eldest daughter.

The delicate outfit is no longer used but Prince George will wear an identical handmade christening gown

He will be baptised over a font that was made for Queen Victoria's first child, with water from the River Jordan.

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The last time three future monarchs were photographed with the Queen was 1894

There will be enormous interest in the pictures taken of the prince - and in one image in particular.

After the service an historic photo will be taken.

It will show the Queen with three future monarchs - her son Charles, her grandson William and her great-grandson George.

It is an image not seen since July 1894.

Then the black and white formal portrait showed the christening of the future Edward VIII.

The photo has him in the arms of his great grandmother Queen Victoria with his father George V and grandfather Edward VII standing behind.

Later, the picture echoing that iconic image will be taken by photographer Jason Bell.

It is believed he was one of a number of photographers interviewed by the duke and duchess.

'Fingers crossed'

He is something of a surprise choice.

His portfolio of work does not include royal events but instead focuses on celebrity portraits for the likes of Vogue and Vanity Fair - including Kate Winslet, David Beckham, Robbie Williams and the cast of Downton Abbey.

Getting the christening photo just right is a stressful assignment for any photographer, according to one veteran of the royal beat, Sun royal photographer Arthur Edwards.

"He's probably down at the palace now checking the lights and setting them up.

"He's probably done it a thousand times, test after test. It'll come to that moment when they sit down and he will have to take the picture and he will take three or four frames.

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The coffin of Princess Diana was placed in the Chapel Royal before her funeral

"His fingers will be crossed and his legs will be crossed hoping that no one blinks."

As king, Prince George will one day be Supreme Governor of the Church of England.

And this afternoon he will be welcomed into the Christian faith.

It will be a private family occasion but also a moment of historic significance.